Investment Firm Drops Stake in Bushmaster Group in Wake of Shooting

iStockphoto/Thinkstock (file photo)(NEW YORK) -- A major investment firm said on Tuesday it is dropping its stake in the group of companies that manufacture the assault-style rifle that officials said was used in last week's rampage at a Connecticut elementary school.

Calling the shooting a "watershed event" in the national debate on gun control, Cerberus Capital, a New York-based firm that manages over $20 billion, said in a statement Tuesday it planned to sell off its investment in the Freedom Group. Freedom Group bills itself as a "family" of more than a dozen firearm companies including Bushmaster Firearms.

Officials said it was a Bushmaster assault-style rifle, the civilian version of the military's M-16, that 20-year-old Adam Lanza used in a majority of the rampage that took the lives of 20 children and six adults at Sandy Hook Elementary School Friday morning.

"It is not our role to take positions, or attempt to shape or influence the gun control policy debate. That is the job of our federal and state legislators," Cerberus said on Tuesday. "There are, however, actions that we as a firm can take. Accordingly, we have determined to immediately engage in a formal process to sell our investment in Freedom Group... Our thoughts and prayers are with the families and communities impacted by this tragic event."

Bushmaster has not responded to an emailed request for comment from ABC News and has not addressed the deadly incident on its website as of this report.

Cerberus' move comes as investigators said they will be going back to the beginning -- back to the day Lanza was born and the day the Bushmaster was manufactured -- in an attempt to figure out what may have caused the troubled young man to so easily get his hands on such a deadly weapon.

Officials said the rifle was purchased legally by Lanza's mother, Nancy, in 2010, well after family friends said Lanza's behavioral issues were clear.

Richard Novia, the advisor for the tech club at Newton High of which Adam was a member until he left the school two years ago, said that Lanza could not feel pain and if he cut or hurt himself, "he would not know it."

Ryan Kraft, a former baby-sitter of Lanza's, said Nancy told him never to leave her son alone, "never even to go to the bathroom or turn [my] back on him at any time."

Police have not said exactly what model of AR-15-type semi-automatic rifle Lanza used -- and Bushmaster offers more than a dozen different types, not to mention a host of modifications that can be made to the guns -- but generally the weapons can take a high-capacity 30-round magazine and have an effective firing rate of 45 shots per minute, according to a Bushmaster manual posted online.

A February report by Guns and Ammo magazine noted a growing demand in recent years for AR-15-type rifles -- and specifically those loaded with .223 caliber bullets as Lanza's was -- for use in home defense. The .223 caliber load is popular, the article says, because it has better fragmentation upon impact, meaning it will deal a lot of damage with less chance of accidentally continuing through the target and endangering whoever's in the background.

"This thing is just a killing machine," Josh Horwitz, Executive Director of the Coalition to Stop Gun Violence, told ABC News Monday. "It's designed, like I said it was designed... very similar to the weapon that's used in the battlefield."

Connecticut's gun laws are some of the toughest in the country, according to anti-gun groups, but they do not specifically ban the Bushmaster AR-15-type guns and the weapon can be easily modified to dodge other restrictions. On Bushmaster's website, the company offers to help customers make sure their assault-style rifles are "state compliant."

"But it's still just as deadly because what makes it dangerous is the ability to take almost unlimited amounts of ammunition and a pistol grip," said Horwitz. "That's what allows the shooter to keep the barrel down on the target."

Forensic psychologist Michael Welner told ABC News on Tuesday that while the shooting has certainly reinvigorated America's decades-old gun debate, the media has been missing an important part of the lesson from the shooting: the crush of media coverage gives mass shooters exactly what they want.

"If you can keep an assault rifle out of his hands the body count will drop, and that's great, but the mass killings will continue to happen unless, systemically, we do address it as a social phenomenon and recognize that there are things that promote it, for example, his picture on our screen and us even caring to go all the way back to find out what his grievance is..." Welner said. "He's looking for legitimacy... [Shooters] want to go from irrelevance to hyper-relevance."